Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition having a nematic phase that includes two components, wherein the first component is a specific compound having negatively large dielectric anisotropy, and the second component is a specific two-ring compound having especially small viscosity, and a liquid crystal display device including the composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serialno. 2007-071992, filed on Mar. 20, 2007. All disclosure of the Japanapplication is incorporated herein by reference. The entirety theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal composition suitable for usein an active matrix (AM) device, and an AM device containing thecomposition. In particular, the invention relates to a liquid crystalcomposition having a negative dielectric anisotropy, and to a devicehaving an IPS (in-plane switching) mode or a VA (vertical alignment)mode containing the composition.

2. Related Art

In a liquid crystal display device, classification based on an operatingmode of liquid crystals includes phase change (PC), twisted nematic(TN), super twisted nematic (STN), electrically controlled birefringence(ECB), optically compensated bend (OCB), in-plane switching (IPS),vertical alignment (VA), and so forth. Classification based on a drivingmode includes a passive matrix (PM) and an active matrix (AM). PM isfurther classified into static, multiplex and so forth, and AM isclassified into a thin film transistor (TFT), a metal insulator metal(MIM) and so forth. TFT is further classified into amorphous silicon andpolycrystal silicon. The latter is classified into a high temperaturetype and a low temperature type according to a production process.Classification based on a light source includes a reflection typeutilizing a natural light, a transmission type utilizing a backlight anda semi-transmission type utilizing both the natural light and thebacklight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship between the general characteristics of thetwo. The general characteristics of the composition will be explainedfurther based on a commercially available AM device. A temperature rangeof a nematic phase relates to the temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or more and a desirable minimum temperature isapproximately −10° C. or less. The viscosity of the composition relatesto the response time of the device. A short response time is desirablefor displaying a moving image. Accordingly, a small viscosity of thecomposition is desirable. A small viscosity at a low temperature is moredesirable.

TABLE 1 General Characteristics of a Liquid Crystal Composition and anAM Device General Characteristics of a No. Composition GeneralCharacteristics of an AM Device 1 Temperature range of a nematic Usabletemperature range is wide phase is wide 2 Viscosity is small¹⁾ Responsetime is short 3 Optical anisotropy is suitable Contrast ratio is large 4An absolute value of dielectric Threshold voltage is low, electric poweranisotropy is large consumption is small, and a contrast ratio is large5 Specific resistance is large Voltage holding ratio is large and acontrast ratio is large 6 It is stable to ultraviolet light and Servicelife is long heat ¹⁾A liquid crystal composition can be injected into acell in a short time.

The optical anisotropy of the composition relates to the contrast ratioof the device. A product (Δn·d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed to maximizethe contrast ratio. A suitable value of the product depends on the kindof operation mode. In a device having a VA mode, a suitable value isfrom approximately 0.30 μm to approximately 0.40 μm. In a device havingan IPS mode, a suitable value is from approximately 0.20 μm toapproximately 0.30 μm. In this case, a composition having a largeoptical anisotropy is desirable for a device having a small cell gap. Alarge dielectric anisotropy of the composition contributes to a lowthreshold voltage, a small electric power consumption and a largecontrast ratio of the device. Accordingly, a large dielectric anisotropyis desirable. A large specific resistance of the composition contributesto a large voltage holding ratio and a large contrast ratio of thedevice. Accordingly, a composition having a large specific resistance isdesirable at room temperature and also at a high temperature in theinitial stage. A composition having a large specific resistance at roomtemperature and also at a high temperature is desirable after it hasbeen used for a long time. A stability of the composition to anultraviolet light and heat relates to a service life of the liquidcrystal device. The service life of the device is long when thestability is high. These characteristics are desirable for an AM deviceused for a liquid crystal projector, a liquid crystal television and soforth.

A composition having a positive dielectric anisotropy is used in an AMdevice having a TN mode. A composition having a negative dielectricanisotropy is used in an AM device having a VA mode. A compositionhaving a positive or negative dielectric anisotropy is used in an AMdevice having an IPS mode. Examples of a liquid crystal compositionhaving a negative dielectric anisotropy are disclosed in the followingpatent documents, JP 2001-115161 A and JP 2001-262145 A.

A desirable AM device is characterized as having a usable temperaturerange that is wide, a response time that is short, a contrast ratio thatis large, a threshold voltage that is low, a voltage holding ratio thatis large, a service life that is long, and so forth. Even onemillisecond shorter response time is desirable. Thus, the compositionhaving characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a large optical anisotropy, a positively or negatively large dielectricanisotropy, a large specific resistance, a high stability to anultraviolet light, a high stability to heat, and so forth is especiallydesirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition having a negativedielectric anisotropy comprising two components, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-1) to formula (1-4), and the second componentis at least one compound selected from the group of compoundsrepresented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons of which arbitrary hydrogen is replacedby fluorine; and Z¹ is a single bond, ethylene, carbonyloxy, ormethyleneoxy.

The invention also concerns a liquid crystal display device thatincludes the liquid crystal composition and so forth.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition and/or the liquid crystal display deviceof the invention may occasionally be expressed simply as “thecomposition” or “the device,” respectively. A liquid crystal displaydevice is a generic term for a liquid crystal display panel and a liquidcrystal display module. The “liquid crystal compound” is a generic termfor a compound having a liquid crystal phase such as a nematic phase, asmectic phase and so forth, and also for a compound having no liquidcrystal phase but being useful as a component of a composition. Theuseful compound contains a 6-membered ring such as 1,4-cyclohexylene and1,4-phenylene, and a rod-like molecular structure. An optically activecompound may occasionally be added to the composition. Even in the casewhere the compound is a liquid crystal compound, the compound isclassified into an additive. At least one compound selected from a groupof compounds represented by formula (1-1) may be abbreviated to “thecompound (1-1).” The term “the compound (1-1)” means one compound or twoor more compounds represented by formula (1-1). The other formulas areapplied with the same rules. The term “arbitrary” means not only anarbitrary position but also an arbitrary number, and the case where thenumber is zero is not included.

A higher limit of a temperature range of a nematic phase may beabbreviated to “a maximum temperature.” A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”“A specific resistance is large” means that the composition has a largespecific resistance at room temperature and also at a high temperaturein the initial stage, the composition has a large specific resistance atroom temperature and also at a high temperature even after it has beenused for a long time. “A voltage holding ratio is large” means that adevice has a large voltage holding ratio at room temperature and also ata high temperature in the initial stage, the device has a large voltageholding ratio at room temperature and also at a high temperature evenafter it has been used for a long time. In the description of thecharacteristics, such as optical anisotropy, the characteristics of thecomposition such as the optical anisotropy and so forth are valuesmeasured in the methods disclosed in Examples. The first component isone compound, or two or more compounds. “A ratio of the first component”means the percentage by weight (% by weight) of the first componentbased on the total weight of liquid crystal composition. A ratio of thesecond component and so forth are applied with the same rule. A ratio ofan additive mixed with the composition means the percentage by weight (%by weight) based on the total weight of liquid crystal composition.

The symbol R¹ is used for many compounds in the chemical formulas forthe component compounds. R¹ may be identical or different in thesecompounds. In one case, for example, R¹ of the compound (1-1) is ethyland R¹ of the compound (1-2) is ethyl. In another case, R¹ of thecompound (1-1) is ethyl and R¹ of the compound (1-2) is propyl. Thisrule is also applicable to the symbols R², Z¹ and so forth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies at least one characteristic among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a negatively large dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light, a highstability to heat and so forth. Another of the advantages of theinvention is to provide a liquid crystal composition that is properlybalanced regarding at least two characteristics among the manycharacteristics. Still another of the advantages of the invention is toprovide a liquid crystal display device that contains the liquid crystalcomposition. One aspect of the invention is to provide a liquid crystalcomposition that has a large optical anisotropy, a negatively largedielectric anisotropy, a high stability to ultraviolet light and soforth, and is to provide an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

The invention has the following features:

1. A liquid crystal composition having a negative dielectric anisotropycomprising two components, wherein the first component is at least onecompound selected from the group of compounds represented by formula(1-1) to (1-4), and the second component is at least one compoundselected from the group of compounds represented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons of which arbitrary hydrogen is replacedby fluorine; and Z¹ is a single bond, ethylene, carbonyloxy, ormethyleneoxy.

2. The liquid crystal composition according to item 1, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-3).

3. The liquid crystal composition according to item 1, wherein the firstcomponent is a mixture of at least one compound selected from the groupof compounds represented by formula (1-1) and at least one compoundselected from the group of compounds represented by formula (1-2).

4. The liquid crystal composition according to item 1, wherein the firstcomponent is a mixture of at least one compound selected from the groupof compounds represented by formula (1-1) and at least one compoundselected from the group of compounds represented by formula (1-3).

5. The liquid crystal composition according to any one of items 1 to 4,wherein a ratio of the first component is from approximately 10% byweight to approximately 55% by weight, and a ratio of the secondcomponent is from approximately 30% by weight to approximately 65% byweight, based on the total weight of the liquid crystal composition.

6. The liquid crystal composition according to any one of items 1 to 5,wherein the composition further comprises at least one compound selectedfrom the group of compounds represented by formulas (3) as a thirdcomponent:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons of which arbitrary hydrogen is replacedby fluorine; ring A, ring B, and ring C are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1, or4-phenylene; and Z¹ and Z² are each independently a single bond,ethylene, carbonyloxy, or methyleneoxy; p is 0,1, or 2; and when Z¹ andZ² are a single bond and p is 0, ring B and ring C are notsimultaneously 1,4-cyclohexylene.

7. The liquid crystal composition according to item 6, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by formula (3-1) to (3-9).

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons; and R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons.

8. The liquid crystal composition according to item 7, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by formula (3-3).

9. The liquid crystal composition according to item 7, wherein the thirdcomponent is a mixture of at least one compound selected from the groupof compounds represented by formula (3-3) and at least one compoundselected from the group of compounds represented by formula (3-5).

10. The liquid crystal composition according to item 7, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-3) and at least onecompound selected from the group of compounds represented by formula(3-7), and at least one compound selected from the group of compoundsrepresented by formula (3-8).

11. The liquid crystal composition according to item 7, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by

formula (3-3), at least one compound selected from the group ofcompounds represented by formula (3-5), and at least one compoundselected from the group of compounds represented by formula (3-9).

12. The liquid crystal composition according to any one of items 6 to11, wherein a ratio of the first component is from approximately 10% byweight to approximately 55% by weight, a ratio of the second componentis from approximately 30% by weight to approximately 65% by weight, aratio of the third component is from approximately 5% by weight toapproximately 35% by weight based on the total weight of the liquidcrystal composition.

13. The liquid crystal composition according to any one of items 1 to12, wherein the composition further comprises at least one compoundselected from the

group of compounds represented by formulas (4) as a fourth component:wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, or alkenyl having 2 to 12 carbons,or alkenyl having 2 to 12 carbons of which arbitrary hydrogen isreplaced by fluorine; ring D is 1,4-cyclohexylene or 1,4-phenylene; Z¹is a single bond, ethylene, carbonyloxy, or methyleneoxy; X¹ is fluorineor chlorine; and q is 0 or 1.

14. The liquid crystal composition according to item 13, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-1) to (4-9).

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons.

15. The liquid crystal composition according to item 14, wherein thefourth component is a mixture of at least one compound selected from thegroup of compounds represented by formula (4-2) and at least onecompound selected from the group of compounds represented by formula(4-9).

16. The liquid crystal composition according to item 14, wherein thefourth component is a mixture of at least one compound selected from thegroup of compounds represented by formula (4-2), at least one compoundselected from the group of compounds represented by formula (4-8), andat least one compound selected from the group of compounds representedby formula (4-9).

17. The liquid crystal composition according to any one of items 13 to16, wherein a ratio of the first component is from approximately 10% byweight to approximately 55% by weight, a ratio of the second componentis from approximately 30% by weight to approximately 65% by weight, anda ratio of the fourth component is from approximately 5% by weight toapproximately 40% by weight, based on the total weight of the liquidcrystal composition.

18. The liquid crystal composition according to any one of items 13 to16, wherein a ratio of the first component is from approximately 10% byweight to approximately 55% by weight, a ratio of the second componentis from approximately 30% by weight to approximately 65% by weight, aratio of the third component is from approximately 5% by weight toapproximately 35% by weight, and a ratio of the fourth component is fromapproximately 5% by weight to approximately 40% by weight, based on thetotal weight of the liquid crystal composition.

19. The liquid crystal composition according to any one of items 1 to18, wherein the composition has a maximum temperature of a nematic phaseof approximately 70° C. or more, an optical anisotropy (25° C.) at awavelength of 589 nm of approximately 0.07 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of approximately −2 or less.

20. A liquid crystal display device that includes the liquid crystalcomposition according to any one of items 1 to 19.

21. The liquid crystal display device according to item 20, wherein theliquid crystal display device has an operation mode of a VA mode or anIPS mode, and has a driving mode of an active matrix mode.

The invention further includes: (1) the composition described above,wherein the composition further contains an optically active compound;(2) the composition described above, wherein the composition furthercontains an additive, such as an antioxidant, an ultraviolet lightabsorbent and/or an antifoaming agent; (3) an AM device containing thecomposition described above; (4) a device having an TN, ECB, OCB, IPS orVA mode, containing the composition described above; (5) a device of atransmission type, containing the composition described above; (6) useof the composition described above as a composition having a nematicphase; and (7) use as an optically active composition by adding anoptically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, the main characteristics of the componentcompounds and the main effects of the compounds on the composition willbe explained. Third, a desirable ratio of the component compounds andthe basis thereof will be explained. Fourth, a desirable embodiment ofthe component compounds will be explained. Fifth, examples of thecomponent compound will be shown. Sixth, additives that may be added tothe composition will be explained. Seventh, the preparation methods ofthe component compound will be explained. Lastly, use of the compositionwill be explained.

First, the constitution of component compounds in the composition willbe explained. The composition of the invention is classified into thecomposition A and the composition B. The composition A may furthercontain another liquid crystal compound, an additive, an impurity, andso forth. Another liquid crystal compound is different from the compound(1-1), the compound (1-2), the compound (1-3), the compound (1-4), thecompound (2), the compound (3), and the compound (4). Such anothercompound is mixed with the composition for the purpose of adjusting thecharacteristics of the composition. Among another liquid crystalcompounds, an amount of a cyano compound is desirably small from theviewpoint of stability to heat or ultraviolet light. The ratio of thecyano compound is more desirably 0% by weight. The additive includes anoptically active compound, an antioxidant, an ultraviolet lightabsorbent, a coloring matter, an antifoaming agent and so forth. Theimpurity is a compound and so forth contaminated in the process such asthe synthesis of a component compound and so forth.

The composition B essentially consists of the compounds selected fromthe compound (1-1), the compound (1-2), the compound (1-3), the compound(1-4), the compound (2), the compound (3), and the compound (4). Theterm “essentially” means that the composition does not contain a liquidcrystal compound which is different from these compounds. The term“essentially” also means that the composition may further contain theadditive, the impurity, and so forth. The components of the compositionB are fewer than those of the composition A. The composition B ispreferable to the composition A from the viewpoint of cost reduction.The composition A is preferable to the composition B, becausecharacteristics of the composition A can be further adjusted by mixingwith other liquid crystal compounds.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of composition will beexplained. The main characteristics of the component compounds aresummarized in Table 2 according to the advantages of the invention. InTable 2, the symbol L represents large or high, the symbol M representsa middle degree, and the symbol S represents small or low. The symbolsL, M and S are classification based on qualitative comparison among thecomponent compounds.

TABLE 2 Characteristics of Compounds Compound (1-1) (1-2) (1-3) (1-4)(2) (3) (4) Maximum S M M M S S-L S-M temperature Viscosity M L L L SS-L M-L Optical S M L M S S-L M-L anisotropy Dielectric M M L L 0 0 Lanisotropy¹⁾ Specific L L L L L L L resistance ¹⁾The value of dielectricanisotropy is negative, and the symbol shows magnitude of an absolutevalue.

The main effects of the component compounds to the characteristics ofthe composition upon mixing the component compounds to the compositionare as follows. The compound (1-1), the compound (1-2), and the compound(1-4) increase an absolute value of the dielectric anisotropy. Thecompound (1-3) increases the optical anisotropy and an absolute value ofthe dielectric anisotropy. The compound (2) decreases the viscosity. Thecompound (3) decreases the minimum temperature. The compound (4)increases an absolute value of the dielectric anisotropy.

Third, desirable ratios of the component compounds and the basistherefor will be explained. A desirable ratio of the first component isapproximately 10% by weight or more for increasing an absolute value ofthe dielectric anisotropy, and is approximately 55% by weight or lessfor decreasing the minimum temperature. A more desirable ratio is fromapproximately 10% by weight to approximately 50% by weight. Aparticularly desirable ratio is from approximately 15% by weight toapproximately 50% by weight.

A desirable ratio of the second component is approximately 30% by weightor more for decreasing the viscosity, and is approximately 65% by weightor less for decreasing the minimum temperature. A more desirable ratiois from approximately 30% by weight to approximately 60% by weight. Aparticularly desirable ratio is from approximately 35% by weight toapproximately 60% by weight.

A desirable ratio of the third component is approximately 35% by weightor less for decreasing the minimum temperature. A more desirable ratiois from approximately 5% by weight to approximately 30% by weight. Aparticularly desirable ratio is from approximately 10% by weight toapproximately 30% by weight.

The fourth component is suitable for preparing a composition having alarge absolute value of a dielectric anisotropy. A desirable ratio ofthe fourth component is from approximately 5% by weight to approximately40% by weight. A more desirable ratio is from approximately 5% by weightto approximately 35% by weight. A particularly desirable ratio is fromapproximately 10% by weight to approximately 35% by weight.

Fourth, a desirable embodiment of the component compound will beexplained. R¹ and R² are each independently alkyl having 1 to 12carbons, alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons of which arbitrary hydrogenis replaced by fluorine. Desirable R¹ and R² are alkyl having 1 to 12 oralkenyl having 2 to 12 carbons for decreasing the minimum temperature orthe viscosity. R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to12 carbons. Desirable R³ is linear alkyl having 1 to 10 carbons forincreasing a stability to ultraviolet light and heat. R⁴ is alkyl having1 to 12 carbons, alkoxy having 1 to 12 carbons, and alkenyl having 2 to12 carbons. Desirable R⁴ is linear alkyl having 1 to 10 carbons forincreasing a stability to ultraviolet light and heat.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,or octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl, orheptyl for decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl for decreasingthe viscosity. A desirable configuration of —CH═CH— in these alkenylsdepends on the position of a double bond. Trans is desirable in thealkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl, and 3-hexenyl for decreasing the viscosity. Cis is desirablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thesealkenyls, linear alkenyl is preferable to branched alkenyl.

Preferred examples of alkenyl, arbitrary hydrogen of which is replacedby fluorine, include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More preferred examples thereof include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Ring A, ring B, and ring C are 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene. Two rings A may beidentical or different when p is 2. Desirable ring A, ring B, and ring Care 1,4-cyclohexylene or 1,4-phenylene for increasing the maximumtemperature and decreasing the viscosity. Ring D is 1,4-cyclohexylene or1,4-phenylene. Desirable ring D is 1,4-phenylene for increasing theoptical anisotropy

Z¹ and Z² are each independently a single bond, ethylene, carbonyloxy,or methyleneoxy. Desirable Z¹ is a single bond for decreasing theviscosity.

X¹ is fluorine or chlorine. Desirable X¹ is fluorine for increasing anabsolute value of the dielectric anisotropy.

P is 0,1, or 2. Desirable p is 1 for decreasing the minimum temperature.

q is 0 or 1. Desirable q is 0 for increasing an absolute value of thedielectric anisotropy.

Fifth, examples of the component compound will be shown. In thedesirable compounds described below, R⁵ is linear alkyl having 1 to 12carbons or linear alkenyl having 2 to 12 carbons. R⁶ is linear alkylhaving 1 to 12 carbons or linear alkoxy having 1 to 12 carbons. In thesecompounds, trans is preferable to cis for the configuration of1,4-cyclohexylene for increasing the maximum temperature.

Desirable compound (1-1) is the compound (1-1-1). Desirable compound(1-2) is the compound (1-2-1). Desirable compound (1-3) is the compound(1-3-1). Desirable compound (1-4) is the compound (1-4-1). Desirablecompound (2) is the compound (2-1). Desirable compounds (3) are from thecompound (3-1-1) to the compound (3-10). More desirable compounds (3)are the compound (3-3-1), the compound (3-5-1), the compound (3-7-1),the compound (3-8-1), and the compound (3-9-1). Particularly desirablecompounds (3) are the compound (3-3-1), the compound (3-5-1), and thecompound (3-7-1). Desirable compounds (4) are from the compound (4-1-1)to the compound (4-9-1). More desirable compounds (4) are the compound(4-2-1), the compound (4-8-1), and the compound (4-9-1).

Sixth, additives capable of being mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent and so forth. An optically active compound is mixed inthe composition for inducing a helical structure of liquid crystal toprovide a twist angle. Examples of the optically active compound includethe compounds (5-1) to (5-4) below. A desirable ratio of the opticallyactive compound is approximately 5% by weight or less, and a moredesirable ratio thereof ranges from approximately 0.01% by weight toapproximately 2% by weight.

An antioxidant is mixed with the composition in order to avoid adecrease in specific resistance caused by heating in the air, or tomaintain a large voltage holding ratio at room temperature and also at ahigh temperature even after the device has been used for a long time.

Preferred examples of the antioxidant include the compound (6):

wherein n is an integer of from 1 to 9. In the compound (6), desirable nare 1, 3, 5, 7, or 9. More desirable n is 1 or 7. When n is 1, thecompound (6) has a large volatility, and is effective in preventing thedecrease of specific resistance caused by heating in the air. When n is7, the compound (6) has a small volatility, and is effective inmaintaining a large voltage holding ratio at room temperature and alsoat a high temperature even after the device has been used for a longtime. A desirable ratio of the antioxidant is approximately 50 ppm ormore for obtaining the advantage thereof and is approximately 600 ppm orless for preventing the maximum temperature from being decreased andpreventing the minimum temperature from being increased. A moredesirable ratio thereof ranges from approximately 100 ppm toapproximately 300 ppm.

Preferred examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer, such as an amine having steric hindranceis also desirable. A desirable ratio of the absorbent and the stabilizeris approximately 50 ppm or more for obtaining the advantage thereof andis approximately 10,000 ppm or less for preventing the maximumtemperature from being decreased and preventing the minimum temperaturefrom being increased. A more desirable ratio thereof ranges fromapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to suit for a device of a guest host (GH) mode. Adesirable ratio of the dye ranges from approximately 0.01% by weight toapproximately 10% by weight. An antifoaming agent such as dimethylsilicone oil or methylphenyl silicone oil is mixed with the compositionfor preventing foaming. A desirable ratio of the antifoaming agent isapproximately 1 ppm or more for obtaining the advantage thereof and isapproximately 1,000 ppm or less for preventing display failure fromoccurring. A more desirable ratio thereof ranges from approximately 1ppm to approximately 500 ppm.

Seventh, the preparation methods of the component compounds will beexplained. These compounds can be prepared by known methods. Thepreparation method will be exemplified below. The compound (1-1-1), thecompound (1-2-1), the compound (1-3-1), and the compound (1-4-1) areprepared by the method disclosed in JP 2000-8040 A. The compound (2-1)and the compound (3-3-1) are prepared by the method disclosed in JPH4-30882 A/1992. The compound (3-9-1) is prepared by the methoddisclosed in JP H2-237949 A/1990. The compound (4-1-1) and the compound(4-5-1) are prepared by the method disclosed in JP H2-503441 A/1990. Theantioxidant is commercially available. The compound (6), wherein n is 1,is available, for example, from Sigma-Aldrich, Corporation. The compound(6), wherein n is 7, is prepared by the method disclosed in U.S. Pat.No. 3,660,505.

The compounds for which preparation methods were not described above canbe prepared according to the methods described in Organic Syntheses(John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.),Comprehensive Organic Synthesis (Pergamon Press), New ExperimentalChemistry Course (Shin Jikken Kagaku Kouza) (Maruzen, Inc.), and soforth. The composition is prepared according to known methods using thecompounds thus obtained. For example, the component compounds are mixedand dissolved in each other by heating.

Last, use of the composition will be explained. Most of the compositionshave a minimum temperature of approximately −10° C. or less, a maximumtemperature of approximately 70° C. or more, and an optical anisotropyof approximately 0.07 to approximately 0.20. The device containing thecomposition has a large voltage holding ratio. The composition issuitable for an AM device. The composition is suitable especially for anAM device of a transmission type. The composition having an opticalanisotropy of approximately 0.08 to approximately 0.25 and furtherhaving an optical anisotropy of approximately 0.10 to approximately 0.30may be prepared by controlling ratios of the component compounds or bymixing other liquid crystal compounds. The composition can be used as acomposition having a nematic phase and as an optically activecomposition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for an AM device or a PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA, and soforth. It is especially desirable to use the composition for an AMdevice having a mode of VA or IPS. These devices may be of a reflectiontype, a transmission type or a semi-transmission type. It is desirableto use the composition for a device of a transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three dimensionalnet-work polymer is formed in the composition. It will be apparent tothose skilled in the art that various modifications and variations canbe made in the invention and specific examples provided herein withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the invention covers the modifications and variations ofthis invention that come within the scope of any claims and theirequivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

When a sample was a composition, it was measured as it was, and theobtained value is described here. When a sample was a compound, a samplefor measurement was prepared by mixing 15% by weight of the compound and85% by weight of mother liquid crystals. A value of characteristic ofthe compound was calculated by extrapolating from a value obtained bymeasurement. Namely: (extrapolated value)={(value measured forsample)−0.85×(value measured for mother liquid crystals)}/0.15. When asmectic phase (or crystals) separated out at this ratio at 25° C., aratio of the compound and mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight), (1% by weight/99% by weight), respectively. Values for amaximum temperature, optical anisotropy, viscosity, and dielectricanisotropy of the compound were obtained by the extrapolation.

The composition of the mother liquid crystals is as shown below.

Measurement of the value of the characteristics was carried outaccording to the following methods. Most methods are described in theStandard of Electric Industries Association of Japan, EIAJ.ED-2521 A orthose with some modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point measuring apparatus equipped with apolarizing microscope and was heated at the rate of 1° C. per minute. Atemperature was measured when a part of the sample began to change froma nematic phase into an isotropic liquid. A higher limit of atemperature range of a nematic phase may be abbreviated to “a maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in a glass vial and then kept in a freezer attemperatures of 0° C., −10° C., −20° C., −30° C., and −40° C. for tendays, respectively, and a liquid crystal phase was observed. Forexample, when the sample remained in a nematic phase at −20° C. andchanged to crystals or a smectic phase at −30° C., Tc was expressed as≦−20° C. A lower limit of a temperature range of a nematic phase may beabbreviated to “a minimum temperature.”

Viscosity (η; measured at 20° C., mPa·s): A viscosity was measured bymeans of an E-type viscometer.

Optical Anisotropy (refractive anisotropy Δn; measured at 25° C.):Measurement was carried out with an Abbe refractometer mounting apolarizing plate on an ocular using a light at a wavelength of 589 nm.The surface of a main prism was rubbed in one direction, and then asample was dropped on the main prism. Refractive index (n∥) was measuredwhen the direction of a polarized light was parallel to that of therubbing. Refractive index (n⊥) was measured when the direction of apolarized light was perpendicular to that of the rubbing. A value ofoptical anisotropy was calculated from the equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at 25° C.): A value of a dielectricanisotropy was calculated from the equation: Δ∈=∈∥−∈⊥. The values ofdielectric constant (∈∥ and ∈⊥) were measured in the following manner.

(1) Measurement of dielectric constant (∈∥): A solution ofoctadecyltriethoxysilane (0.16 mL) dissolved in ethanol (20 mL) wascoated on a glass substrate having been well cleaned. The glasssubstrate was rotated with a spinner and then heated at 150° C. for 1hour. A sample was charged in a VA device having a distance (cell gap)of 4 μm between two sheets of the glass substrates, and the device wassealed with an adhesive capable of being cured with ultraviolet light.Sine waves (0.5 V, 1 kHz) were applied to the device, and after lapsingtwo seconds, a dielectric constant (∈∥) in the major axis direction ofthe liquid crystal molecule was measured.

(2) Measurement of dielectric constant (∈⊥): Polyimide was coated on aglass substrate having been well cleaned. The glass substrate was baked,and the resulting orientation film was subjected to a rubbing treatment.A sample was charged in a TN device having a distance between two sheetsof the glass substrates (cell gap) of 9 μm and a twisted angle of 80°.Sine waves (0.5 V, 1 kHz) were applied to the device, and after lapsingtwo seconds, a dielectric constant (∈⊥) in the minor axis direction ofthe liquid crystal molecule was measured.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with LCD Evaluation System Model LCD-5100 made by Otsuka ElectronicsCo., Ltd. The light source was a halogen lamp. A sample was poured intoa VA device of a normally black mode, in which a cell gap between twoglass plates was 4 μm, and a rubbing direction was antiparallel, and thedevice was sealed with a UV curing adhesive. Voltage to be applied ontothe device (60 Hz, rectangular waves) was increased stepwise by 0.02 Vstarting from 0 V up to 20 V During the stepwise increasing, the devicewas irradiated with light in a perpendicular direction, and an amount ofthe light passing through the device was measured. Voltage-transmissioncurve was prepared, in which a maximum amount of a light corresponded to100% transmittance, a minimum amount of a light corresponded to 0%transmittance. Threshold voltage is a value at 10% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass plates is 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive which is polymerized by theirradiation of an ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). Decreasing voltagewas measured for 16.7 milliseconds with High Speed Voltmeter and thearea A between a voltage curve and a horizontal axis in a unit cycle wasobtained. The area B was an area without decreasing. Voltage holdingratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass plates is 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive which is polymerized by theirradiation of an ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). Decreasing voltagewas measured for 16.7 milliseconds with High Speed Voltmeter and thearea A between a voltage curve and a horizontal axis in a unit cycle wasobtained. The area B was an area without decreasing. Voltage holdingratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): After irradiatingwith ultraviolet light, a voltage holding ratio was measured to evaluatestability to ultraviolet light. A composition having large VHR-3 has alarge stability to ultraviolet light. A TN device used for measurementhas a polyimide-alignment film and the cell gap is 5 μm. A sample waspoured into the device, and then the device was irradiated with lightfor 20 minutes. The light source was a superhigh voltage mercury lampUSH-500D (produced by Ushio, Inc.), and the distance between the deviceand the light source is 20 cm. In measurement of VHR-3, a decreasingvoltage is measured for 16.7 milliseconds. VHR-3 is desirably 90% ormore, and more desirably 95% or more.

Voltage holding ratio (VHR-4; measured at 25° C.; %): A voltage holdingratio was measured after heating an TN device having a sample pouredtherein in a constant-temperature bath at 80° C. for 500 hours toevaluate stability to heat. A composition having large VHR-4 has a largestability to heat. In measurement of VHR-4, a decreasing voltage wasmeasured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; ms): Measurement was carried outwith LCD Evaluation System Model LCD-5100 made by Otsuka ElectronicsCo., Ltd. Light source is a halogen lamp. Low-pass filter was set at 5kHz. A sample was poured into a VA device of a normally black mode, inwhich a cell gap between two glass plates was 4 μm, and a rubbingdirection was antiparallel, and the device was sealed with a UV curingadhesive. Rectangle waves (60 Hz, 10 V, 0.5 seconds) were applied to thedevice. During application, the device was irradiated with

light in a perpendicular direction, and an amount of the light passingthrough the device was measured. A maximum amount of a light correspondsto 100% transmittance, and a minimum amount of a light corresponds to 0%transmission. Response time is a period of time required for the changein transmittance from 90% to 10% (fall time: ms).

Specific Resistance (ρ; measured at 25° C.; Ωcm): 1.0 mL of a sample wascharged in a vessel equipped with electrodes. A direct current voltageof 10 V was applied to the vessel, and after lapsing 10 second from theapplication of voltage, the direct electric current was measured. Thespecific resistance was calculated by the equation: (specificresistance)={(voltage)×(electric capacity of vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

Gas Chromatographic Analysis: A Gas Chromatograph Model GC-14B made byShimadzu was used for measurement. The carrier gas was helium (2milliliters per minute). An evaporator and a detector (FID) were set upat 280° C. and 300° C., respectively. Capillary column DB-1 (length 30meters, bore 0.32 millimeters, film thickness 0.25 micrometers,dimethylpolysiloxane as stationary phase, no polarity) made by AgilentTechnologies, Inc. was used for the separation of the componentcompound. After the column had been kept at 200° C. for 2 minutes, itwas further heated to 280° C. at the rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and 1 microliterof the solution was injected into the evaporator. The recorder used wasChromatopac Model C-R5A made by Shimadzu or its equivalent. Gaschromatogram obtained showed a retention time of a peak and a peak areacorresponding to the component compound.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary columns may also be used for theseparation of the component compound: HP-1 made by Agilent TechnologiesInc. (length 30 meters, bore 0.32 millimeters, film thickness 0.25micrometers), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeters, film thickness 0.25 micrometers), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeters, filmthickness 0.25 micrometers). In order to prevent compound peaks fromoverlapping, a capillary column CBP1-M50-025 (length 50 meters, bore0.25 millimeters, film thickness 0.25 micrometers) made by ShimadzuCorporation may be used.

The ratios of the liquid crystal compounds contained in the compositioncan also be calculated in the following manner. A liquid crystalcompound can be detected by gas chromatography. An area ratio of peakson a gas chromatogram corresponds to a ratio (molar number) of liquidcrystal compounds. In the case where the aforementioned capillarycolumns are used, correction coefficients of the liquid crystalcompounds can be regarded as 1. Accordingly, the ratio (% by weight) ofliquid crystal compounds is calculated from the area ratio of peaks.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsdescribed in the Comparative Examples and the Examples are expressed bythe symbols according to the definition in Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbernext to the symbolized compounds in the Examples corresponds to thenumber of the desirable compound. The symbol (-) means other liquidcrystal compound. A ratio (percentage) of a liquid crystal compound ispercentage by weight (% by weight) based on the total weight of a liquidcrystal composition. The liquid crystal composition further contains theimpurity. Last, the characteristics of the composition are summarized.

TABLE 3 Method of Description of Compound using Symbols R-(A₁)-Z₁- . . .-Z_(n)-(A_(n))-R′ 1) Left Terminal Group R- Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- 2) Right Terminal Group - Symbol—C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1)-Vn —C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ —VFF —COO—CH₃ -EMe 3) Bonding Group-Z_(n)- Symbol —C₂H₄— 2 —COO— E —CH₂O— 1O 4) Ring Structure -A_(n)-Symbol

H

B

B(F)

B(2F)

B(2F,3F)

B(F,CL)

dh

Dh 5) Example of Description Example 1. 3-dhBB(2F,3F)-O2

Example 2. 3-HH—V

Example 3. 5-HBB(F)B-3

Comparative Example 1

Example 12 was chosen from the compositions disclosed in JP 2001-115161A. The basis is that the composition contains the compounds (2-1), thecompounds (3-1-1), the compounds (3-3-1), and the compounds similar tothe compounds (1-1) or the compound (1-2). The components andcharacteristics of the composition were as follows.

3-Dh2B(2F,3F)-O2 (—) 3% 3-DhB(2F,3F)-O2 (—) 3% 5-DhB(2F,3F)-O2 (—) 6%3-HDhB(2F,3F)-O1 (—) 7% 3-HDhB(2F,3F)-O2 (—) 7% 3-HH-4 (2-1) 12% 3-HB-O2(3-1-1) 16% 3-HB-O4 (3-1-1) 8% 2-HH-EMe (—) 6% 3-HH-EMe (—) 10% 3-HHB-1(3-3-1) 7% 3-HHB-3 (3-3-1) 10% 3-HHB-O1 (3-3-1) 5%The composition has the following characteristics: NI=72.0° C.; Tc≦−20°C.; Δn=0.076; Δ∈=−1.2; η=16.2 mPa·s.

Example 1

The composition of Example 1 had a small viscosity as compared to thecomposition of Comparative Example 1.

2-dhB(2F,3F)-O2 (1-1-1) 5% 3-dhB(2F,3F)-O2 (1-1-1) 5% 5-dhB(2F,3F)-O2(1-1-1) 7% 3-HdhB(2F,3F)-O2 (1-2-1) 7% 2-dhBB(2F,3F)-O2 (1-3-1) 6%3-dhBB(2F,3F)-O2 (1-3-1) 7% 4-dhHB(2F,3F)-O2 (1-4-1) 6% 5-dhHB(2F,3F)-O2(1-4-1) 6% 3-HH-V (2-1) 40% 3-HH-V1 (2-1) 11% NI = 73.8° C.; Tc ≦ −20°C.; Δn = 0.075; Δε = −3.1; η = 14.8 mPa · s.

Example 2

The composition of Example 2 had a small viscosity as compared to thecomposition of Comparative Example 1.

2-dhBB(2F,3F)-O2 (1-3-1) 10% 3-dhBB(2F,3F)-O2 (1-3-1) 10%4-dhBB(2F,3F)-O2 (1-3-1) 10% 5-dhBB(2F,3F)-O2 (1-3-1) 10% 3-HH-V (2-1)49% 3-HH-V1 (2-1) 11% NI = 88.2° C.; Tc ≦ −20° C.; Δn = 0.100; Δε =−3.5; η = 15.0 mPa · s.

Example 3

The composition of Example 3 had a small viscosity as compared to thecomposition of Comparative Example 1.

2-dhB(2F,3F)-O2 (1-1-1) 5% 3-dhB(2F,3F)-O2 (1-1-1) 5% 5-dhB(2F,3F)-O2(1-1-1) 5% 2-HdhB(2F,3F)-O2 (1-2-1) 10% 3-HdhB(2F,3F)-O2 (1-2-1) 10%5-HdhB(2F,3F)-O2 (1-2-1) 10% 3-HH-V (2-1) 45% 3-HH-V1 (2-1) 10% NI =70.4° C.; Tc ≦ −20° C.; Δn = 0.066; Δε = −2.2; η = 15.5 mPa · s.

Example 4

2-dhB(2F,3F)-O2 (1-1-1) 5% 3-dhB(2F,3F)-O2 (1-1-1) 5% 2-dhBB(2F,3F)-O2(1-3-1) 8% 3-dhBB(2F,3F)-O2 (1-3-1) 8% 4-dhBB(2F,3F)-O2 (1-3-1) 7%5-dhBB(2F,3F)-O2 (1-3-1) 7% 3-HH-V (2-1) 49% 3-HH-V1 (2-1) 11% NI =74.3° C.; Tc ≦ −20° C.; Δn = 0.085; Δε = −3.1; η = 15.3 mPa · s.

Example 5

2-dhB(2F,3F)-O2 (1-1-1) 5% 3-dhB(2F,3F)-O2 (1-1-1) 5% 2-HdhB(2F,3F)-O2(1-2-1) 5% 3-HdhB(2F,3F)-O2 (1-2-1) 5% 2-dhBB(2F,3F)-O2 (1-3-1) 10%3-dhBB(2F,3F)-O2 (1-3-1) 10% 3-HH-V (2-1) 38% 3-HH-V1 (2-1) 7% V-HHB-1(3-3-1) 9% V2-HHB-1 (3-3-1) 6% NI = 87.5° C.; Tc ≦ −20° C.; Δn = 0.089;Δε = −2.1; η = 15.0 mPa · s.

Example 6

2-dhB(2F,3F)-O2 (1-1-1) 5% 3-dhB(2F,3F)-O2 (1-1-1) 5% 3-HdhB(2F,3F)-O2(1-2-1) 5% 2-dhBB(2F,3F)-O2 (1-3-1) 6% 3-dhBB(2F,3F)-O2 (1-3-1) 7%4-dhBB(2F,3F)-O2 (1-3-1) 6% 5-dhBB(2F,3F)-O2 (1-3-1) 6% 3-HH-V (2-1) 40%V-HHB-1 (3-3-1) 10% 2-BB(F)B-3 (3-5-1) 10% NI = 86.9° C.; Tc ≦ −20° C.;Δn = 0.108; Δε = −1.8; η = 16.0 mPa · s.

Example 7

V-dhB(2F,3F)-O2 (1-1-1) 8% V2-dhB(2F,3F)-O2 (1-1-1) 12% V-HdhB(2F,3F)-O2(1-2-1) 10% V-dhBB(2F,3F)-O2 (1-3-1) 5% 3-HH-V (2-1) 39% 3-HH-O1 (2-1)6% V-HHB-1 (3-3-1) 5% 3-HHEH-3 (3-7-1) 5% 3-HHEH-4 (3-7-1) 5% 3-HHEBH-3(3-8-1) 5% NI = 78.2° C.; Tc ≦ −20° C.; Δn = 0.070; Δε = −1.5; η = 15.7mPa · s.

Example 8

3-HdhB(2F,3F)-1 (1-2-1) 5% 2-dhBB(2F,3F)-1 (1-3-1) 8% 3-dhBB(2F,3F)-1(1-3-1) 8% 4-dhBB(2F,3F)-1 (1-3-1) 7% 5-dhBB(2F,3F)-1 (1-3-1) 7% 3-HH-V(2-1) 47% V-HHB-1 (3-3-1) 5% V2-BB(F)B-1 (3-5-1) 5% 5-HBB(F)B-2 (3-9-1)8% NI = 102.5° C.; Tc ≦ −30° C.; Δn = 0.115; Δε = −2.1; η = 16.0 mPa ·s.

Example 9

2-dhBB(2F,3F)-O2 (1-3-1) 5% 3-dhBB(2F,3F)-O2 (1-3-1) 10% 3-HH-V (2-1)40% V-HHB-1 (3-3-1) 13% 3-H2B(2F,3F)-O2 (4-2-1) 12% 5-H2B(2F,3F)-O2(4-2-1) 10% 3-HBB(2F,3F)-O2 (4-9-1) 10% NI = 71.7° C.; Tc ≦ −20° C.; Δn= 0.089; Δε = −2.9; η = 14.0 mPa · s.

Example 10

2-dhBB(2F,3F)-O2 (1-3-1) 7% 3-dhBB(2F,3F)-O2 (1-3-1) 8% 4-dhBB(2F,3F)-O2(1-3-1) 8% 5-dhBB(2F,3F)-O2 (1-3-1) 7% 3-HH-V (2-1) 45% 3-H2B(2F,3F)-O2(4-2-1) 9% 3-HBB(F,CL)-O2 (4-8-1) 5% 3-HBB(2F,3F)-O2 (4-9-1) 11% NI =86.3° C.; Tc ≦ −20° C.; Δn = 0.104; Δε = −4.1; η = 16.0 mPa · s.

Example 11

2-dhBB(2F,3F)-1 (1-3-1) 6% 3-dhBB(2F,3F)-1 (1-3-1) 7% 4-dhBB(2F,3F)-1(1-3-1) 6% 5-dhBB(2F,3F)-1 (1-3-1) 6% 3-HH-V (2-1) 40% V2-BB-1 (3-2-1)5% 3-HBB-2 (3-4-1) 5% 2-BBB(2F)-3 (3-6-1) 5% 5-HB(F)BH-2 (3-10) 7%3-HB(2F,3F)-O2 (4-1-1) 10% 1O1-HBBH-5 (—) 3% NI = 90.2° C.; Tc ≦ −20°C.; Δn = 0.110; Δε = −1.6; η = 16.0 mPa · s.

Example 12

2-dhBB(2F,3F)-1 (1-3-1) 6% 3-dhBB(2F,3F)-1 (1-3-1) 7% 4-dhBB(2F,3F)-1(1-3-1) 6% 5-dhBB(2F,3F)-1 (1-3-1) 6% 3-HH-V (2-1) 45% 3-HHB(F,CL)-O2(4-4-1) 12% 3-HHB(2F,3F)-1 (4-5-1) 10% 3-HH2B(2F,3F)-O2 (4-6-1) 8% NI =84.5° C.; Tc ≦ −20° C.; Δn = 0.090; Δε = −3.8; η = 15.9 mPa · s.

Example 13

2-dhBB(2F,3F)-O2 (1-3-1) 6% 3-dhBB(2F,3F)-O2 (1-3-1) 8% 4-dhBB(2F,3F)-O2(1-3-1) 8% 5-dhBB(2F,3F)-O2 (1-3-1) 8% 2-HH-3 (2-1) 15% 2-HH-5 (2-1) 3%3-HH-VFF (2) 12% 3-HB-O2 (3-1-1) 10% 3-H1OB(2F,3F)-O2 (4-3-1) 10%3-HH1OB(2F,3F)-O2 (4-7-1) 10% 5-HH1OB(2F,3F)-O2 (4-7-1) 10% NI = 87.0°C.; Tc ≦ −20° C.; Δn = 0.100; Δε = −4.6; η = 16.0 mPa · s.

Example 14

2-dhB(2F,3F)-O2 (1-1-1) 5% 3-dhB(2F,3F)-O2 (1-1-1) 5% 3-HdhB(2F,3F)-O2(1-2-1) 7% 2-dhBB(2F,3F)-O2 (1-3-1) 6% 3-dhBB(2F,3F)-O2 (1-3-1) 7%4-dhHB(2F,3F)-O2 (1-4-1) 6% 5-dhHB(2F,3F)-O2 (1-4-1) 6% 3-HH-V (2-1) 40%3-HH-V1 (2-1) 11% 1O1-HBBH-5 (—) 7% NI = 80.8° C.; Tc ≦ −30° C.; Δn =0.090; Δε = −2.3; η = 15.8 mPa · s.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

1. A liquid crystal composition having a negative dielectric anisotropycomprising two components, wherein the first component is at least onecompound selected from the group of compounds represented by formulas(1-1) to (1-4), and the second component is at least one compoundselected from the group of compounds represented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons of which arbitrary hydrogen is replacedby fluorine; and Z¹ is a single bond, carbonyloxy, or methyleneoxy. 2.The liquid crystal composition according to claim 1, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-3).
 3. The liquid crystal compositionaccording to claim 1, wherein the first component is a mixture of atleast one compound selected from the group of compounds represented byformula (1-1) and at least one compound selected from the group ofcompounds represented by formula (1-2).
 4. The liquid crystalcomposition according to claim 1, wherein the first component is amixture of at least one compound selected from the group of compoundsrepresented by formula (1-1) and at least one compound selected from thegroup of compounds represented by formula (1-3).
 5. The liquid crystalcomposition according to claim 1, wherein a ratio of the first componentis from approximately 10% by weight to approximately 55% by weight, anda ratio of the second component is from approximately 30% by weight toapproximately 65% by weight, based on the total weight of the liquidcrystal composition.
 6. The liquid crystal composition according toclaim 1, wherein the composition further comprises at least one compoundselected from the group of compounds represented by formulas (3) as athird component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons of which arbitrary hydrogen is replacedby fluorine; ring A, ring B, and ring C are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or3-fluoro-1,4-phenylene; Z¹ and Z² are each independently a single bond,ethylene, carbonyloxy or methyleneoxy; p is 0, 1, or 2; and when Z¹ andZ² are a single bond and p is 0, ring B and ring c are notsimultaneously 1,4-cyclohexylene.
 7. The liquid crystal compositionaccording to claim 6, wherein the third component is at least onecompound selected from the group of compounds represented by formula(3-1) to formula (3-9):

wherein R³ is alkyl having 1 to 12 carbons, or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons.
 8. The liquid crystalcomposition according to claim 7, wherein the third component is atleast one compound selected from the group of compounds represented byformula (3-3).
 9. The liquid crystal composition according to claim 7,wherein the third component is a mixture of at least one compoundselected from the group of compounds represented by formula (3-3) and atleast one compound selected from the group of compounds represented byformula (3-5).
 10. The liquid crystal composition according to claim 7,wherein the third component is a mixture of at least one compoundselected from the group of compounds represented by formula (3-3), atleast one compound selected from the group of compounds represented byformula (3-7), and at least one compound selected from the group ofcompounds represented by formula (3-8).
 11. The liquid crystalcomposition according to claim 7, wherein the third component is amixture of at least one compound selected from the group of compoundsrepresented by formula (3-3), at least one compound selected from thegroup of compounds represented by formula (3-5), and at least onecompound selected from the group of compounds represented by formula(3-9).
 12. The liquid crystal composition according to claim 6, whereina ratio of the first component is from approximately 10% by weight toapproximately 55% by weight, a ratio of the second component is fromapproximately 30% by weight to approximately 65% by weight, and a ratioof the third component is from approximately 5% by weight toapproximately 35% by weight based on the total weight of the liquidcrystal composition.
 13. The liquid crystal composition according toclaim 1, wherein the composition further comprises at least one compoundselected from the group of compounds represented by formula (4) as afourth component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, or alkenyl having 2 to 12 carbons,or alkenyl having 2 to 12 carbons of which arbitrary hydrogen isreplaced by fluorine; ring D is 1,4-cyclohexylene, or 1,4-phenylene; Z¹is a single bond, ethylene, carbonyloxy or methyleneoxy; X¹ is fluorineor chlorine; and q is 0, or
 1. 14. The liquid crystal compositionaccording to claim 6, wherein the composition further comprises at leastone compound selected from the group of compounds represented by formula(4) as a fourth component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, or alkenyl having 2 to 12 carbons,or alkenyl having 2 to 12 carbons of which arbitrary hydrogen isreplaced by fluorine; ring D is 1,4-cyclohexylene or 1,4-phenylene; Z¹is a single bond, ethylene, carbonyloxy or methyleneoxy; X¹ is fluorineor chlorine; and q is 0, or
 1. 15. The liquid crystal compositionaccording to claim 13, wherein the fourth component is at least onecompound selected from the group of compounds represented by formulas(4-1) to (4-9):

wherein R³ is alkyl having 1 to 12 carbons, or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons.
 16. The liquid crystalcomposition according to claim 14, wherein the fourth component is atleast one compound selected from the group of compounds represented byformulas (4-1) to (4-9):

wherein R³ is alkyl having 1 to 12 carbons, or alkenyl having 2 to 12carbons; R⁴ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons.
 17. The liquid crystalcomposition according to claim 15, wherein the fourth component is amixture of at least one compound selected from the group of compoundsrepresented by formula (4-2) and at least one compound selected from thegroup of compounds represented by formula (4-9).
 18. The liquid crystalcomposition according to claim 16, wherein the fourth component is amixture of at least one compound selected from the group of compoundsrepresented by formula (4-2) and at least one compound selected from thegroup of compounds represented by formula (4-9).
 19. The liquid crystalcomposition according to claim 15, wherein the fourth component is amixture of at least one compound selected from the group of compoundsrepresented by formula (4-2), at least one compound selected from thegroup of compounds represented by formula (4-8), and at least onecompound selected from the group of compounds represented by formula(4-9).
 20. The liquid crystal composition according to claim 16, whereinthe fourth component is a mixture of at least one compound selected fromthe group of compounds represented by formula (4-2), at least onecompound selected from the group of compounds represented by formula(4-8), and at least one compound selected from the group of compoundsrepresented by formula (4-9).
 21. The liquid crystal compositionaccording to claim 13, wherein a ratio of the first component is fromapproximately 10% by weight to approximately 55% by weight, a ratio ofthe second component is from approximately 30% by weight toapproximately 65% by weight, and a ratio of the fourth component is fromapproximately 5% by weight to approximately 40% by weight based on thetotal weight of the liquid crystal composition.
 22. The liquid crystalcomposition according to claim 14, wherein a ratio of the firstcomponent is from approximately 10% by weight to approximately 55% byweight, a ratio of the second component is from approximately 30% byweight to approximately 65% by weight, a ratio of the third component isfrom approximately 5% by weight to approximately 35% by weight, and aratio of the fourth component is from approximately 5% by weight toapproximately 40% by weight, based on the total weight of the liquidcrystal composition.
 23. The liquid crystal composition according toclaim 1, wherein the composition has a maximum temperature of a nematicphase of approximately 70° C. or more, an optical anisotropy (25° C.) ata wavelength of 589 nm of approximately 0.07 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of approximately −2.0 orless.
 24. A liquid crystal display device that includes the liquidcrystal composition according to claim
 1. 25. The liquid crystal displaydevice according to claim 24, wherein the liquid crystal display devicehas an operation mode of a VA mode or an IPS mode, and has a drivingmode of an active matrix mode.